President Donald Trump made good on his campaign promises for "extreme vetting" Friday afternoon, signing an executive memorandum that makes sweeping changes to U.S. refugee and immigration policy the White House says is designed to protect the nation from terrorists who want to enter the country.

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The seven-page document calls for an immediate suspension of immigration from countries with ties to terror, including Syria, Yemen, Sudan, Somalia, Iraq, Iran and Libya, for a time period of 90 days. It also calls for the complete suspension of Syrian refugees for an indefinite period.

In both cases, the executive order says admissions from these regions are "detrimental to the United States."

The order also calls on the secretary of state to suspend the entire Refugee Admissions Program (meaning all countries) for 120 days while authorities review the application and adjudication process.

President Trump signed the order, called "Protecting the Nation From Foreign Terrorist Entry Into the United States," Friday afternoon after an official swearing-in ceremony for his new secretary of defense, James Mattis.

The order also calls for limiting the overall number of refugees admitted to the U.S. to 50,000 people in 2017. Last fiscal year, the Obama White House admitted close to 85,000 refugees, over 12,500 of them from Syria.

In addition, the order also calls for prioritizing refugee entry on the basis of "religious-based persecution" so long as the religion is a minority in the country of the person seeking refuge. That language appears to be directed in part at Syrian Christians, a group Trump has singled out as a priority. To that effect, the order says that exceptions to the immigration and refugee policies outlined in the document can be made on a case-by-case basis.

Reaction from around the world was swift. The refugee advocacy group The International Refugee Assistance Project called Friday announcement a "betrayal of the fundamentally American value of welcoming those who are fleeing persecution."

Malala Yousafzai, a Pakistani human rights advocate and Nobel Prize recipient, said in a statement Friday that she is "heartbroken" by the decisions.

"I am heartbroken that today President Trump is closing the door on children, mothers and fathers fleeing violence and war," Yousafzai wrote in a Facebook post. "I am heartbroken that America is turning its back on a proud history of welcoming refugees and immigrants -- the people who helped build your country, ready to work hard in exchange for a fair chance at a new life. I am heartbroken that Syrian refugee children, who have suffered through six years of war by no fault of their own, are singled out for discrimination."

President Trump spoke at the Pentagon Friday about the executive order.

"I’m establishing new vetting measures to keep radical Islamic terrorists out of the United States of America. We don’t want them here," Trump said. "We only want to admit those into our country who will support our country and love deeply our people."

In anticipation of the order, more than 2,000 religious leaders from across the country signed a letter to President Trump in opposition to any policy change that would bar refugees based on their religion or nationality. The letter called for keeping the U.S. Refugee Resettlement Program "open to those of all nationalities and religions who face persecution on account of the reasons enumerated under U.S. law."

"We oppose any policy change that would prevent refugees from Syria, Iraq, Iran, Libya, Somalia, Sudan, and Yemen, or individuals who practice Islam and other faiths from accessing the U.S. Refugee Resettlement Program," said the letter.

The International Rescue Committee (IRC), which responds to humanitarian disasters around the world, said that Trump's suspension of the U.S. resettlement program was a “harmful and hasty” decision. The organization, which provides aid to refugees around the world, said in a statement that the impact would be felt by mostly women and children awaiting resettlement.

"In truth, refugees are fleeing terror -- they are not terrorists,” said IRC President and CEO David Miliband. “And at a time when there are more refugees than ever, America must remain true to its core values. America must remain a beacon of hope."